The present invention relates generally to a pad for use in the application of ultrasound energy to a target object. In particular, the present invention is directed to a pad that provides ultrasound transmissive contact between an ultrasound probe and a target object. The present invention further is directed to a method for the administration of medical compounds to target body tissues through the use of ultrasound energy and a pad containing a couplant containing one or more medical compounds.
Ultrasound imaging and pulse-echo technology have been widely used in the medical field for diagnostic testing and therapeutic purposes. Ultrasound imaging also has been used in industrial applications for the purpose of evaluating the structural integrity of castings and forgings in order to identify delaminations, voids, cracks, and deficiencies in weld integrity. Ultrasound imaging also has been used for the purpose of detecting spoilage or contamination of food products.
It has been discovered that ultrasound energy tends to cause a disorientation of a target tissue, thus increasing the permeability of the tissue and making possible the transdermal administration of a variety of substances. Transdermal drug deliver (TDD) offers several advantages over traditional drug delivery methods. For example, TDD avoids gastrointestinal drug metabolism, reduces elimination of the drug by the liver, and provides sustained release of the administrated drug. TDD also avoids the pain associated with drug injections and intravenous administration.
In order to utilize ultrasound imaging, it is necessary to establish an interface between the ultrasound probe and the target surface. This interface has commonly been created by placing a couplant gel between the probe and the target surface prior to directing ultrasound energy to the target surface. In the alternative, some systems create the requisite interface by directing a continuous stream of water between the target surface and the ultrasound probe. Finally, some systems employ an immersion technique in order to provide the requisite couplant.
Ultrasound gels are used as couplants in most medical applications of ultrasound energy. Use of these gels can be messy and labor-intensive. The continuous stream and immersion techniques are more typically used in industrial applications and require relatively sophisticated and expensive equipment in order to provide the requisite amount of water and to drain water that is used.
One method for eliminating the use of gels or flowing liquids as couplants entails the use of a dry couplant pad made of a compliant, encapsulated epoxy material attached as a facing to an ultrasound-transducer wedge. However, the solid couplant used in the pad tends to have a lower ultrasound energy transmission efficiency than a liquid or gel couplant.